An organic thin-film solar cell being one of photoelectric conversion devices, which is lighter in weight and more flexible, for example, than a silicon solar cell or the like and can be manufactured at a low cost, attracts attention as a next-generation solar cell.
The organic thin-film solar cell is provided between an anode and a cathode, and has a photoelectric conversion element which has a photoactive layer forming pn junction. In the organic thin-film solar cell, as a result that irradiated light such as sunlight is absorbed by the active layer, excitons are generated by photoexcitation and diffused to a pn junction interface, where charge separation is carried out to make obtained electrons migrate to a cathode side as well as to make positive holes migrate to an anode side, whereby power generation is performed.
The photoactive layer in the organic thin-film solar cell is quite easy to be deteriorated under an air atmosphere or the like, since an organic semiconductor is used therein. Thus, in the organic thin-film solar cell, a sealing layer is formed between an element substrate in which the photoelectric conversion element is provided and a counter substrate, whereby a sealing region which seals at least the photoactive layer is formed. At this time, if a sealing failure such as unapplying, uncuring, or deterioration of the sealing layer occurs, an impurity such as oxygen or water enters the sealing region, to deteriorate the photoactive layer. Deterioration of the photoactive layer is one of causes of reduction of a conversion efficiency.
However, checking a state of sealing is difficult and inspecting whether or not the impurity has entered the sealing region has been difficult. For example, if an impurity concentration in the sealing region can be determined in a manufacturing stage, it becomes possible to ship only a good-quality product without sealing failure.